1. Technical Field
Embodiments of the present disclosure relate generally to data converters, and more specifically to achieving high dynamic range in a sigma delta analog to digital converter.
2. Related Art
Analog to digital converters (ADC) are often implemented employing sigma delta (also termed delta sigma) modulation techniques. As is well known in the relevant arts, a sigma delta (SD) ADC is a type of ADC which includes a sigma delta modulator followed by a digital decimation filter. The sigma delta modulator receives an analog input signal which is sought to be represented in digital form, and generates a digital stream of noise-shaped output digital values corresponding to the analog input signal, each output digital value being represented either by a single bit or multiple bits. The sigma delta modulator uses closed-loop feedback to generate the output digital values, as is also well-known in the relevant arts. The digital decimation filter decimates (filtering/down-sampling of the output digital stream) to generate a final digital representation of the analog input signal.
Dynamic range with respect to a SD ADC generally refers to the ratio of the largest and smallest magnitudes of the analog input signal that the SD ADC can resolve and convert to digital form. Thus, dynamic range refers to the range between the noise floor of the SD ADC and the maximum output level the SD ADC can handle. Dynamic range may also be viewed as being correlated with the signal-to-noise-ratio (SNR) of the output of the SD ADC, a larger SNR corresponding to a larger dynamic range. A high dynamic range is usually desirable in a SD ADC. Further, such a high dynamic range may need to be achieved or provided even when one or more design constraints are imposed on the design of the SD ADC.